SKY73208-11 Datasheet, PDF (6/17 Pages) Skyworks Solutions Inc. – 350-5000 MHz Wideband Receive Mixer with Integrated Integer-N PLL and VCO

DATA SHEET • SKY73208-11: MIXER WITH PLL AND VCO
The R_DIV register stores the value of the 11-bit R-divider that
produces the desired comparison frequency (FCOMP) for the RF PLL
according to the following equation:
R

F_REF
F_COMP
(3)
Where FREF is the reference frequency provided to the device.
The N_DIV1 and N_DIV2 registers store the value of the N-divider
according to the following equation:
N

F_VCO
F_REF
R
(4)
Bits[1:0] of the N_DIV2 register are the most significant bits
(MSBs) of the 18-bit representation of the N number.
Bits[15:0] of the N_DIV1 register are the LSBs of the 18-bit binary
representation of the N number.
The calculated R-divider and N-divider values are programmed
into the SKY73208-11 using the SPI interface.
Additional programming information is provided in the document,
Skyworks Wideband, Integer-N Phase-Locked Loop Programming
Guide, document number 201322.
Example:
A desired RF output frequency of 1800 MHz is required using a
reference frequency of 76.8 MHz and a desired frequency step
size of 400 kHz. If the VCO divider is equal to 2, the VCO
frequency is 3600 MHz from Equation 1 and the comparison
frequency is equal to 800 kHz from Equation 2.
From Equations 3 and 4, the R and N values become:
R = 96 = 1100000b
N = 4500 = 1000110010100b
These values would be programmed through the SPI interface.
Figure 5 represents the bits of the R_DIV register with the value of
R = 96. Figures 6 and 7 represent the bits of the N_DIV1 and
N_DIV2 registers, respectively, with the value of N = 4500.
24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0 11 0 0 0 1 0 0 x x x x x 0 0 0 0 1 1 0 0 0 0 0
4-Bit Device
Address
5-Bit Register
Address
11-Bit R-Divider Value
Note: Value of bits [15:11] can vary. Refer to the Skyworks Wideband, Integer-N Phase-Locked Loop Programming Guide, document number 201322.
S1847b
Figure 5. R_DIV Register Showing an R-Divider Value of 96
24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0 11 0 0 0 0 1 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0
4-Bit Device
Address
5-Bit Register
Address
LSBs of 18-Bit
N-Divider Value
Figure 6. N_DIV1 Register Showing an N-Divider Value of 4500 (LSBs)
S1849b
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
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November 5, 2015 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201317F